Processing of ceramics

pigne-caltagirone

Preparation of the clayey mixture

The clay, taken from the quarry, is transported to the company and placed in a special farmyard where it will undergo a seasoning of about a year during which, the organic substances still present, can be transformed as a result of the oxygenation process favored by the succession of weathering. After curing, it is taken and taken to a large dissolver or Turbo dissolver where it will dissolve with the water which has the task of washing the clay and dispersing the soluble salts.

Following the dissolution, the slurry of clay is passed through a special vibrating sieve, which has the purpose of retaining the impurities present in the clay and the more granular particles. Sieved, it is conveyed to a containment pit where a slow agitator keeps it constantly in suspension, preventing it from settling on the bottom. From the containment tank, by means of a diaphragm pump it is conducted and compressed in a filter press consisting of a set of plates covered with filtering sheets that allow the separation of water from the clay and the firming of the latter. After a time of 6/8 hours, the clay is taken out of the discs and brought to the mixing and degassing phase, through special machines called kneading-degassing machines in which the clay is homogenized in the absence of air.

Shaping

From the outlet of the degassing mixers, the clay is brought to the various processes that can be carried out either manually or with the help of molding machines by molding.

 

Manual shaping: the manual turning performed on the lathe, is used for the shaping of pottery or round objects, the potter in fact, with the only help of the hands, is able to give the clay the desired shape.

 

Press molding: For the realization of objects of which a large number of pieces must be reproduced quickly, the molding technique is adopted, with the use of hydraulic presses on which a special mold is mounted.

 

Molding for casting: In this case, kaolin clays of whitish color are adopted, which are dissolved in water together with a fluidifying agent such as sodium silicate, the slip thus obtained, is poured into special molds where it remains for about an hour, after which the mold it is emptied and then opened in order to remove and refine the object formed around the internal walls of the mold.

Drying

The shaped objects require a drying time for the evaporation of the residual water contained in the clay. This process can occur naturally by exposing objects to air, or forced through the use of dryers.

First cooking

Once dried, the products are placed in an oven which can be electrically or gas powered. The first firing in about 12 hours, will bring the objects to a temperature of about 1000 degrees centigrade, followed by the subsequent and gradual cooling, which occurs naturally by heat dissipation, or forcibly in about 24/48 hours, depending on the size of the objects and the mass that was placed in cooking.

Glazing

After the first firing, the objects can be subjected to glazing which is carried out manually by immersing the object in an aqueous solution of glaze. The enamel is made up of a composition of glass, opacifiers and fluxes finely ground in a special mill, in the composition ratio given by the temperature to which it will have to be subjected. The enamelling can also be done with an airbrush in a special booth. It serves to coat the surface of the object on which the decoration will then be applied.

 

Decoration

In ceramic craftsmanship, the decoration is done by hand by skilled decorators, capable of expressing on the surface of the glaze, decorations applied with suitable brushes in order to cover the object with decorations of complete meaning. For this purpose, ceramic colors are used consisting of mineral or metallic oxides mixed with fluxes, in the right quantity in relation to the temperature of the second firing. The greater or lesser harmonization between the applied decoration, the use of color and the shape of the object will then constitute the elements of qualitative evaluation of the artifacts.

Second firing

After the decoration, the object is placed again in the oven to be subjected to a second firing which in 8/10 hours will bring the objects to the temperature of 920/950 degrees centigrade with a further cooling time of about 18/24 hours. The result is an artifact of high value, known as majolica, which has made Caltagirone one of the major production centers.

Processing and Decoration of TILES

CEAR ceramiche is above all synonymous with technical experience acquired within the company throughout the entire production range.

Even for tiles and special pieces such as bulls, pencils, etc., the process starts from the production of clays internally and by means of a special die-cutting system the various formats 10x10 - 15x15 - 20x20 are produced while by extrusion from a special mixer degasser the various special pieces are produced.  For this purpose, pure clay is used to produce compact tiles and commonly used additives such as pozzolanic sand are not used as this type of artifacts have revealed their limits above all in mechanical resistance, abrasion due to trampling, and the resistance of the glaze in surface.

A first firing cycle at 990 ° C allows the tiles to be brought to the maximum degree of vitrification of the mixture.

After the first firing, the tiles are suitably glazed with suitable glazes and are subjected to decoration.

This phase, which is the most important, is characterized by the following process:

the decoration to be created comes first from an in-depth research of the styles linked to our tradition and, substantially, to the Arab one from which it derives and whose survey was conducted not only in Sicily, but also in Spain and Portugal where the Arabs left an undisputed artistic baggage still visible.

Our tiles, in order to guarantee the maximum added value for the use of the decoration that is made strictly by hand, are decorated using the "dusting" a traditional technique that involves the execution of the design on a sheet of transparency, where small holes are produced that reproduce the path of the decoration in the same way as one proceeds in the construction of decorations in embroidery. Then, using a pad made of coal dust, the decoration is transferred onto the tile, and skilled decorators, on the remaining trace, will proceed to carry out the decoration completely by hand, passing the various colors and contours. In this way, the authenticity of a decoration is guaranteed Handmade, but also the continuity and regularity of the same, in the various tiles that like a mosaic compose beautiful designs.